Question

radius
fibia
femur
fibula

Explanation:

The blue - colored bones in the image are the femurs. The femur is the thigh bone, which connects the hip to the knee. The radius is a bone in the forearm, the tibia is the shinbone (lower leg), and the fibula is also a lower - leg bone. By comparing the structure and location of the blue bones (connecting the pelvis to the lower - leg bones) with the characteristics of these bones, we can identify them as femurs.

Answer:

femur